Photoflash lamp



N. F. BAIRD PHOTOFLASH LAMP Nov. 30, 1965 Filed May 25, 1962 FIG. 5.

FIG.3.

FIG. I.

FIG.2.

FlG.6.

PELLETS 7O POWDER 64 FIG. 9.

FIG. 8.

FIG.

INVENTOR. NORMAN F. BAlRD.

FIG. ll. 96

United States Patent C 3,220,224 PHOTOFLASH LAMP Norman F. Baird, Bloomfield, N.J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed May 25, 1962, Ser. No. 197,639 18 Claims. (Cl. 67-31) This invention relates to photoflash lamps and, more particularly, to photoflash lamps having plastic envelopes and actinic-light-producing material for use with photoflash lamps.

The usual commercially produced photoflash lamp comprises a sealed glass envelope which encloses an oxygen atmosphere and a combustible material such as zirconium, magnesium or aluminum, shredded as foil. A small amount of primer material, such as a mixture of powdered zirconium and potassium perchlorate, is ignited by an electrically energized filament. The resulting combustion causes the foil to react with the oxygen atmosphere to produce the desired flash of light. Such a lamp is protected with an organic lacquer coating placed on the outside surface of the lamp envelope, or on both the inside and outside envelope surfaces, in order to prevent rupture of the glass envelope when the lamp is fired.

From the standpoint of cost of manufacture, and also safety of operation, it would be highly desirable to eliminate the glass envelope and provide the photoflash lamp with a light-transmitting plastic envelope of fairly heavy wall thickness. Such lamps have been proposed, but have never been a commercial success, since a plastic envelope per se will not contain an oxygen atmosphere over a prolonged storage period. When the oxygen diffuses through the plastic envelope, leaving a residual atmosphere of air at atmospheric pressure, the actinic reaction which occurs when the shredded foil is ignited produces only a small amount of light.

Other photoflash lamp designs which have been suggested utilize plastic envelopes which are specially designed to release the pressures generated when the lamp is fired. The resulting product is not commercially acceptable, however, because of the noise and odor which result from the escaping gases generated by the actinic or flash-producing reaction.

It is the general object of this invention to provide an improved photoflash lamp which utilizes a plastic envelope, and which lamp can be manufactured very cheaply.

It is another object to provide a plastic-envelope photoflash lamp which operates with a high margin of safety and will not produce any appreciable noise or odors when fired.

It is a further object to provide an improved photoflash lamp which utilizes a plastic envelope and requires no special gas filling.

It is an additional object to provide specific details of construction for an improved plastic-envelope-type photoflash lamp.

It is still another object to provide a photoflash lamp having a spectral output which can be modified without the use of special light-absorbing lacquer coatings.

It is yet another object to provide a photoflash lamp in which the flash-producing materials are so disposed as to generate a flash of light with good efficiency.

It is a further object to provide specific flash-producing materials for use in conjunction with photoflash lamps.

The aforesaid objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by providing a photoflash lamp having a plastic envelope formed of high-tensile-strength, light-transmitting, organic plastic of relatively heavy wall thickness, and which envelope encloses a predetermined volume of air at atmospheric pressure. This plastic enve- 3,226,224 Patented Nov. 30, 1965 lope is hermetically sealed against rupture under -condi-. tions of heat and pressure. Metallic leads extend into the envelope and support an igniter which is adapted to be fired to produce a limited combustion reaction. An actinic-light-producing or flash-producing material is contained within the envelope and principally comprises a mixture of a predetermined amount of finely divided, solid, oxygen-liberating substance and a predetermined amount of finely divided metallic substance. When this mixture is ignited, the resulting reaction proceeds at a predetermined rate under high-pressure conditions to produce a flash of light. The flash-producing mixture is substantially physically separated from both the igniter and the metallic supports. When the igniter is fired, the resulting combustion serves to ignite the flash-producing material. There is also provided specific flash-producing material which will produce a bright flash of light with.- out the generation of explosive pressures when the actinic reaction occurs in a relatively small, enclosed volume. There is additionally provided a photoflash lamp in which the flash-producing materials are so disposed as to generate light with good efiiciency.

For a better understanding of the invention, reference should be had to the accompanying drawings, wherein:

FIGURE 1 is an elevational view, partly in section, of a photoflash lamp fabricated in accordance with the present invention and provided with a molded plastic base;

FIG. 2 is a plan view of the lamp as shown in FIG. 1 illustrating the positioning of the flash-producing mate; rial on the dome portion of the lamp envelope;

FIG. 3 is an elevational view, partly in section, showing an alternative embodiment of the lamp illustrated in FIG. 1, wherein the flash-producing material is carried in part on the side portion of the envelope wall, and the lamp is provided with a so-called M-2 type base;

FIG. 4 is a plan view, partly .in section, of the lamp embodiment of FIG. 3, showing in more detail the positioning of the flash-producing material on the dome and side portions of the lamp envelope;

FIG. 5 is an enlarged, fragmentary, sectional elevation of the base portion of the lamp as shown in FIGS. 3 and 4;

FIG. 6 is an elevational view, partly in section, showing an alternative embodiment of the lamp as illustrated in FIG. 3, wherein the flash-producing material is in powdered form, with the lamp positioned in the horizontal or usual firing position;

FIG. 7 is an elevational view, partly in section, showing "another alternative embodiment of the lamp as illustrated in FIG. 3, wherein the flash-producing material is in the form of a plurality of beads or pellets, and wherein the lamp is positioned in the horizontal or usual firing position;

FIG. 8 is an elevational view, partly in section, of a glass-envelope photoflash lamp, modified to incorporate the improved flash-producing material of the present invention;

FIG. 9 is an elevational view, partly in section, showing a tubular-type photoflash lamp which is fabricated in accordance with the present invention;

FIG. 10 is a plan view of the lamp as shown in FIG. 9; and

FIG. 11 is an elevational view, partly in section, showing a tubular-type lamp generally similar to the lamp embodiment illustrated in FIG. 9, but modified in that only one end of the tubular envelope need be sealed during manufacture.

The present invention is particularly applicable to smaller size photoflash lamps and such types have been illustrated and will be described. It should be understood, however, that the teachings of the present invention are applicable to any size of photoflash lamp.

With specific reference to the form of the invention illustrated in the drawings, the lamp 20 shown in FIG. 1, comprises a plastic envelope 22 having a dome portion 24 and a neck portion 26. The plastic envelope is closed at its neck portion in such manner as to be effectively sealed against rupture under conditions of heat and pressure. Two metallic, electric lead-in conductors 28 extend into the envelope 22 and support a firing filament 30 between their inwardly extending extremities. A glass or plastic spacing bead 32 serves to space and secure the lead-in conductors 28. A small amount of primer material 34 is carried on the inwardly extending extremities of the lead-in conductors 28 and also contacts the firing filament 30. The flash-producing mixture is carried as a thin layer 36 on the dome portion '24 of the envelope 22.

The lead-in conductors 28 extend exterior to the lamp and are conformed about the molded base portion 38 of the lamp 20, in order to provide electrical contacts to facilitate firing the filament 30. Such a lamp base construction is generally disclosed in US. Patent 3,016,727, dated January 16, 1962, except that the present base 38 is formed of molded plastic.

As a specific example, the envelope 22 encloses a volume of 7.3 cc. of air at atmospheric pressure. The envelope 22 is formed of cellulose acetate propionate and has a wall thickness of 40 mils. Preferably, there is only suificient plasticizer in the plastic of the envelope 22 to enable it to be molded, such as parts by weight of plasticizer per 100 parts by weight of the propionate. The firing filament 30 is conventional and formed of tungsten. The igniter or primer 34 is present in an amount of 6 milligrams and preferably is formed of a mixture of finely divided zirconium and potassium perchlorate in such relative proportions. that all of the oxygen in the perchlorate will react with all the zirconium during firing. The flashproducing material layer 36 is present in an amount of 90 milligrams and is formed of a mixture of finely divided zirconium and finely divided barium nitrate, strontium nitrate, or potassium chlorate, or mixtures thereof. The molar ratio of zirconium combustible to oxidant is 3:1. While the envelope is preferably formed of cellulose acetate propionate, other suitable plastics can be substituted therefor, such as cellulose acetate butyrate.

In the lamp embodiment as shown in FIG. 1, the flash-producing mixture is completely separated from the igniting filament and the lead-in conductors 28. When the lamp is fired by igniting the primer material 34, the burning material strikes against the layer 36 of the. flashproducing mixture, in order to generate the desired flash of light. When the strontium nitrate oxidant is used, the

'called "time-to-peak-intensity can be controlled very accurately. The total light output for this specific lamp is slightly less than is normally obtained with a so-called M-2 photoflash lamp or a so-called AG-l photofiash lamp. As tested with actual photographs, however the effective light output of the present lamps is equivalent to that obtained from the AG1 lamp, since this latter lamp emits light over a much longer duration and the speed of the camera shutter cuts off the trailing portions of the light emission.

The lamp embodiment 40, as shown in FIGS. 3 and 4, is modified with respect to the base 42 and the positioning of the layer 44 of flash-producing material which is also carried on a side portion of the envelope 46. In other respects, this lamp embodiment is generally similar to the lamp 20 as shown in FIG. 1, with the total amount of flash-producing material being the same. The base construction of the lamp 40 is shown in FIG. 5, wherein the envelope neck portion 48 has a metallic base shell 50 sealed thereto by means of epoxy resin. One of the leadin conductors 52 extends axially through the base shell 50 and makes contact with a conducting eyelet 54, to which it is soldered. The other lead-in conductor 56 is curved around the envelope neck portion 48 and electrically connects to the base shell 50. The base shell 50 is insulated from the eyelet 54 by a glass insert 58. In order to retain the lead-in conductors in position, and to strengthen the base of the lamp, the major portion of the base shell 50 is filled with epoxy resin 60.

The lamp embodiment 62, as shown in FIG. 6, corresponds to that embodiment as shown in FIGS. 3 through 5, except that the flash-producing material is formed as a powder 64, with the total amount of flash-producing material being the same as hereinbefore described In addition, the lead-in conductors 66 are bent proximat to their inwardly extending extremities.

The lamp embodiment 68 as shown in FIG. 7 generally corresponds to the lamp shown in FIGS. 3 through 5, except that the flash-producing material is in the form of beads or pellets 70, in an amount equivalent to that which was used when this material was placed in the form of a thin layer. If the lamp embodiments 62 and 68, as shown in FIGS. 6 and 7, are fired in a vertical position with the base down, the flash-producing powder 64 or pellets 70 will gravitate to the neck portions of the envelopes, and a very small percentage of the powder or pellets will contact the metallic lead-in conductors. This decreases the light output somewhat, but the powder or pellets will still be substantially physically separated from the lead-in conductors.

The flash-producing material of the present invention must be specially chosen so that when ignited, it will produce a bright flash of light under high-pressure conditions. There are many flash-producing materials which will produce a very bright flash of light when the reaction is not confined, but the flash-producing characteristics of most mixtures are greatly impaired when the reaction is completely confined. Some flash-producing mixtures will produce a relatively bright flash of light when enclosed, such as a mixture of zirconium and potassium perchlorate, but in the presence of an air atmosphere, the reaction is so violent as to generate destructive pressures, even when used with a very heavy-wall plastic envelope.

In accordance with the present invention, the flashproducing material comprises a mixture of finely divided metallic substance and finely divided, solid, oxygen-liberating substance. The finely divided metallic substance is zirconium which desirably has an average particle diameter of from about 1.6 microns to 2.1 microns, with the optimum average particle diameter being about 1.8 microns. The finely divided, oxygen-liberating substance is preferably strontium nitrate or barium nitrate, and potassium chlorate can be used if light output is to be sacrificed. Thus the oxidant is selected from at least one material of the group consisting of strontium nitrate, barium nitrate, and potassium chlorate. The oxidant preferably ha an average particle diameter of from about 1 micron to about 8.5 microns, with the optimum average particle diameter for the oxidant being from 4 microns to 5.5 microns. Preferably, very finely divided silicon dioxide in an amount of about 1% by weight of the flashproducing mixture is added to the mixture in order to make it flow more readily and to facilitate mixing and handling.

The preferred relative molar proportions of zirconium. combustible to oxidant in the present flash-producing ma terial are from 2:1 to 4:1, with the optimum molar proportions of combustible to oxidant being from 2.4:1 to 3.15:1. The flash-producing material is preferably included within the lamp envelope in an amount of from 7.5 to 19 milligrams per cubic centimeter of volume enclosed by the envelope and the optimum amount of fiash-producing material has been found to be from l0 ports proximate to the filament.

milligram of combustible.

milligram to 13 milligrams per cubic centimeter of volume enclosed by the lamp envelope.

Very many different materials have been tested with respect to their flash-producing characteristics under enclosed conditions. The only practical combustible material is finely divided zirconium, as indicated. Of the three enumerated oxygen-liberating materials, strontium nitrate is most efiicient with respect to generating the maximum amount of light, although barium nitrate has been found to be quite good. Barium nitrate is preferred over the strontium nitrate where the lamps are to be stored under extreme conditions of humidity and temperature. In the case of potassium chlorate oxidant, the light output is decreased about 40%, as compared to an equivalent mixture using strontium nitrate.

The foregoing fiash-producing mixture can be controlled with respect to obtaining different spectral outputs. It has been found that with a larger amount of available oxygen, the spectral distribution of the flash will be shifted toward the shorter wavelengths. A smaller amount of available oxygen will shift the output toward the longer wavelengths. In addition, the larger the average particle size of the oxidant, the bluer the appearance. Thus by controlling the relative molar proportions of combustible to oxidant and varying the particle size of the oxidant, the lamp spectral distribution can be modified in accordance with the intended use for the lamp. The igniter also has effect on the spectral distribution and if the igniter does not bridge the filament, the spectral distribution of the flash is shifted somewhat toward the blue, apparently because of a different rate of burning of the flash-producing mixture. This foregoing is advantageous since the usual photofiash lamp must be provided with a blue lacquer coating over the envelope to adapt it for use with certain types of film. Such a blue lacquer coating detracts from the total light emission. This unwanted absorption of light is readily eliminated with the present fiash-producing mixture.

The efficiency of combustion of the present flash-producing mixture is approximately 55 lumen seconds per milligram of material and better efficiencies have been obtained. This is to be compared with the conventional SM-type lamp which utilizes a mixture of zirconium and potassium perchlorate carried directly on the lead-in sup- Even with an oxygen gas fill in a large volume, glass envelope, the efficiency of the SM lamp is only about 55 lumen seconds per Because of the efiicient com bustion of the present fiash-producing mixture, this mate'rial can be used in conjunction with a more conventional photofiash lamp. Such a lamp embodiment 72 is shown in FIG. 8 wherein the construction is generally similar to the usual photofiash lamp, including the glass envelope 74, the protecting exterior lacquer coating 76, the firing filament 78, and the igniter 80. The lamp is modified, however, in that a coating 82 of nitrocellulose or ethyl cellulose desirably is placed over the interior surface of the glass dome portion of the envelope 74. The layer 84 of the fiash-producing mixture of the present invention is placed over this cellulose layer 82. With an oxygen-gas fill, the molar ratio of available oxygen in the flash-producing mixture can be reduced somewhat and such a lamp will be a very efficient generator of light.

The layer 82 of nitrocellulose or ethyl cellulose between the glass envelope 74 and the layer 84 of flashproducing material in the lamp embodiment 72 has been found to enhance the light output. Such an intermediate layer has also been found to be desirable for use with some types of plastics, such as cellulose acetate, in order to enhance the light output obtainable from a lamp which uses a plastic envelope and an air fill.

Due to the low cost of manufacture, it is preferred to use a plastic envelope which encloses air at atmospheric 6 pressure. It has been found that the longer the path of travel through which the combustible mixture can burn, the more efficient the reaction. In FIGS. 9 and 10 is shown a lamp embodiment 86 wherein the envelope 88 is formed of plastic tubing. Both ends of the envelope tubing 88 are heat sealed and the fiash-producing mixture is positioned as a layer 90 at one sealed end of the tubing 88, with the igniting filament 92 and primer 94 positioned at the other end of the tubing 88. This lamp embodiment 86 is similar to that shown in FIGS. 1 and 2 with respect to amounts of igniter and flash-producing material, except that the envelope tubing 88 encloses a total volume of 4.4 cc. Because of the longer path of travel for the burning actinic materials, the light ouput is equivalent to that of the lamp 20, as shown in FIG. 1.

In the lamp embodiment 96 as shown in FIG. 11, the envelope tubing 98 is preformed with a closed end so that only one end need be heat sealed during the lamp fabrication. In other respects, this embodiment is similar to that shown in FIGS. 9 and 10.

The foregoing lamp embodiments are subject to further modification. For example, it has been found desirable to coat the lead-in conductors of any of these lamp embodiments with a thin film of ethyl cellulose or nitrocellulose. This has the effect of increasing somewhat the total light output which can be obtained. In any of the lamps of the present invention, the layer of flashproducing material can be applied to the inner surface of the envelope by mixing 9 grams of the flash-producing mixture with 2.5 cc. of amyl acetate vehicle and nitrocellulose binder in amount of 19.5 percentby weight of the fiash-producing material. The resulting slurry is then painted or otherwise applied as a thin layer to the interior surface of the envelope in the desired total amount. The solvent is then volatilized, the lead-in conductors, primer and filament placed into the envelope through the open neck, and the plastic neck heat sealed about the lead-in conductors. The lamp base can be molded at the same time. Alternatively, a separate base can be applied to complete the lamp fabrication. As can be seen, the manufacture of the plastic-envelope lamp of the present invention involves only a few steps, all of which can be carried out on automatic equipment. The flash-producing material can also be applied to a separate support, such as a strip of paper. The coated paper is then inserted into the envelope before sealing, or adhered to the wall of the envelope before sealing,

In all the lamp embodiments as illustrated and described hereinbefore, the fiash-producing mixture is sub stantially physically separated from the lamp igniter, the filament, and the metallic supports or lead-in conductors. If the fiash-producing material were to be carried on such lead-in supports, as in the case of the conventional SM-type lamp, the light output would be considerably reduced since these metallic supports would absorb a large amount of heat from the fiash-producing reaction.

As indicated hereinbefore, the lamps of the present invention have certain technical advantages in that the color of the emission can be varied without resorting to special lacquer coatings. In addition, the extremely heavy plastic wall minimizes the hazard of a violent failure. The main advantage of plastic-envelope lamps, however, at least from a practical standpoint, is the cost of manufacture, which is approximately one-half that of the standard photofiash lamp of comparable size.

It will be recognized that the objects of the invention have been achieved for providing an improved photofiash lamp which utilizes a plastic envelope and which can be manufactured very cheaply. In addition, this lamp can operate with a high margin of safety and will not produce any appreciable noise or odors when fired. There has also been provided specific fiash-producing material for use in photofiash lamps, as well as a photofiash lamp in which the flash-producing materials are so disposed as to generate a flash of light with good efficiency.

While best embodiments of the invention have been illustrated and described hereinbefore, it is to be particularly understood that the invention is not limited thereto or thereby.

I claim as my invention:

1. The photoflash lamp combination which comprises: an envelope formed of high-strength, light-transmitting organic plastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; metallic support means extending into said envelope; igniter means supported within said envelope by said metallic support means and adapted to be fired to produce a limited combustion reaction; flash-producing means enclosed by said envelope and substantially physically separated from said igniter means and any metallic support means; said flash-producing means principally comprising a mixture of a predetermined amount of selected, finely divided, solid, oxygen-liberating substance and a predetermined amount of selected, finely divided, metallic substance which when ignited react with one another at a predetermined rate under high-pressure conditions to produce a flash of light; and said flash-producing means and said igniter means being so arranged with respect to one another that firing said igniter means ignites said flash-producing means.

2. The photoflash lamp combination as specified in claim 1, wherein said flash-producing means is formed as a supported thin layer.

3. The photoflash lamp combination as specified in claim 1, wherein said flash-producing means is formed as a powder.

4. The photoflash lamp combination as specified in claim 1, wherein said flash-producing means is formed as a plurality of pellets.

5. The photoflash lamp combination which comprises: an envelope formed of high-tensile-strength, light-transmitting, organic thermoplastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; metallic support means extending into said envelope; igniter means supported within said envelope by said metallic support means and adapted to be fired to produce a limited combustion reaction; flashproducing means adhered as a layer on the inner surface of said envelope and substantially physically separated from said igniter means and any metallic support means; said flash-producing means principally comprising a mixture of a predetermined amount of selected, finely divided, solid, oxygen-liberating substance and a predetermined amount of selected, finely divided, metallic substance which when ignited react with one another at a predetermined rate under high-pressure conditions to produce a flash of light; and said flash-producing means and said igniter means being so arranged with respect to one another that firing said igniter means ignites said flash-producing means.

6. The photoflash lamp combination as specified in claim 5: wherein said metallic support means comprises a pair of spaced lead-in conductors having a filament supported between their inwardly extending extremities, and said igniter means is supported proximate to and in contact with said filament; said envelope having a neck portion through which said lead-in conductors are sealed; a metallic base shell fitting about the neck portion of said envelope; a resin filling in the bottom portion of said base shell and sealing said base shell to the neck portion of said envelope and also sealing the neck portion of said envelope against rupture under conditions of heat and pressure; one of said lead-in conductors sealed through said resin filling and contacting said base shell to form one electrical connection for firing said lamps; and the other of said lead-in conductors sealed through said resin filling and axially extending through said base shell to form the other electrical connector for firing said lamp.

7. The photoflash lamp combination which comprises: an envelope formed of high-strength, light-transmitting, organic thermoplastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; metallic support means extending through and into said envelope; igniter means supported within said envelope by said metallic support means and adapted to be fired to produce a limited combustion reaction; flash-producing means enclosed by said envelope and substantially physically separated from said igniter means and any metallic support means, said flash-producing means principally comprising a mixture of a predetermined amount of finely divided zirconium and a predetermined amount of at least one finely divided oxidant of the group consisting of strontium nitrate, barium nitrate and potassium chlorate; and said flash-producing means and said igniter means being so arranged with respect to one another that firing said igniter means ignites said flash-producing means.

8. The photoflash lamp combination which comprises: an envelope formed of high-strength, light-transmitting, organic thermoplastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; metallic support means extending through and into said envelope; igniter means supported within said envelope by said metallic support means and adapted to be fired to produce a limited combustion reaction; flash-producing means contained within said envelope in amount of from 7.5 mg. to 19 mg. per cubic centimeter of volume enclosed by said envelope and also substantially physically separated from said igniter means and any metallic supports; said flash-producing means principally comprising amixture of finely divided zirconium having an average particle diameter of from about 1.6 to 2.1 microns and a finely divided oxidant having an average particle diameter of from about 1 to 8.5 microns; said oxidant selected from at least one material of the group consisting of strontium nitrate, barium nitrate and potassium chlorate; the relative molar proportions of zirconium to oxidant in said flash-producing means being from 2:1 to 4: 1; and said flash-producing means and said igniter means being so arranged With respect to one another that firing said igniter means ignites said flash producing means.

9. The photoflash lamp combination as specified in claim 8, wherein said oxidant principally comprises strontium nitrate.

10. The photoflash 'lamp combination as specified in claim 8, wherein said oxidant principally comprises barium nitrate.

11. The photoflash lamp combination as specified in claim 8, wherein said envelope has a neck portion and a dome portion oppositely disposed from such envelope neck portion, said metallic support means is hermetically sealed through the neck portion of said envelope, and a substantial portion of said flash-producing means is adhered on the inner surface of the dome portion of said envelope.

12. The photoflash lamp combination which comprises: an envelope formed of high-tensile-strength, flight-transmitting, organic thermoplastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; metallic support means extending through and into said envelope; igniter means supported within said envelope by said metallic support means and adapted to be fired to produce a limited combustion reaction; flash-producing means contained within said envelope in amount of from 10 mg. to 13 mg. per cubic centimeter and also substantially physically separated from said igniter means and any metallic support means; said flash-producing means principally comprising a mixture of finely divided zirconium having an average particle diameter of about 1.8 microns and finely divided strontium nitrate having an average particle diameter of from about 4 to 5.5 microns, the relative molar proportions of zirconium to strontium nitrate in said flash-pro ducing means being from 2.4:1 to 3.15:1, and said flashproducing means and said igniter means being so arranged with respect to one another that firing said igniter means ignites said flash-producing means.

13. A photoflash lamp comprising: an envelope formed of light-transmitting organic plastic material enclosing a predetermined volume; igniter means within said envelope and adapted to be fired to produce a priming function; said envelope sealed against rupture under conditions of heat and pressure; flash-producing material positioned proximate and adhered onto the inner surface of said envelope and substantially physically separated from said igniter means; said flash-producing material principally comprising a mixture of a predetermined amount of finely divided zirconium and a predetermined amount of at least one oxidant .of the group consisting of strontium nitrate, barium nitrate and potassium chlorate; and said flash-producing material adapted to be ignited by said igniter means to produce an actinic reaction.

14. A photoflash lamp specified in claim 13, wherein a thin layer of at least one material of the group consisting of nitrocellulose and ethyl cellulose is carried on the interior surface of said envelope intermediate such interior surface and said flash-producing material.

15. A photoflash lamp comprising: an envelope formed of high-strength, light-transmitting, organic thermoplastic material enclosing a predetermined volume; igniter means within said envelope and adapted to be fired to produce a priming function; said envelope sealed against rupture under conditions of heat and pressure; flash-producing material contained within said envelope and substantially physically separated from said igniter means; said flashproducing material principally comprising a mixture of a predetermined amount of finely divided zirconium and a predetermined amount of at least one oxidant of the group consisting of strontium nitrate, barium nitrate and potassium chlorate; the relative molar proportions of zirconium to oxidant in said flash-producing material being from 2:1 to 4: 1; and said flash-producing material adapted to be ignited by said ignite-r means to produce an actinic reaction.

16. A photoflash lamp comprising: an envelope formed of high-tensile-strength, light-transmitting, organic thermoplastic material enclosing a predetermined volume; igniter means within said envelope and adapted to be fired to produce a priming function; said envelope sealed against rupture under conditions of heat and pressure; flash-producing material contained within said envelope in amount of from 7.5 to 19 mg. per cc. of volume enclosed by said envelope and substantially physically separated from said igniter means; said flash-producing material principally comprising a mixture of finely divided zirconium having an average particle diameter of from about 1.6 to 2.1 microns, and finely divided oxidant having an average particle diameter of from about 1 to 8.5 microns; said oxidant selected from at least one material of the group consisting of strontium nitrate, barium nitrate and potassium chlorate; the relative molar proportions of zirconium to oxidant in said flash-producing material being from 2:1 to 4:1; and said flash-producing material adapted to be ignited by said igniter means.

17. The photoflash lamp combination which comprises: a tubular-shaped envelope formed of high-strength, lighttransmitting organic plastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; metallic support means extending through said envelope and into one end of said envelope; igniter means supported within and proximate to one end of said envelope by said metallic support means and adapted to be fired to produce a limited combustion reaction; flash-producing means enclosed by said envelope and carried proximate to the other end of said envelope; said flash-producing means principally comprising a mixture of a predetermined amount of preselected, finely divided, oxygen-containing substance and a predetermined amount of preselected, finely divided, metallic substance which when ignited react with one another at a predetermined rate under high-pressure conditions to produce a flash of light; and said igniter means being so arranged that firing said igniter means ignites said flash-producing means.

18. The photoflash lamp combination which comprises: an envelope formed of high-strength, light-transmitting, organic plastic of predetermined thickness enclosing a predetermined volume of air at atmospheric pressure and sealed against rupture under conditions of heat and pressure; igniter means supported within said envelope and adapted to be fired to produce a limited combustion reaction; flash-producing means adhered on and positioned proximate the inner surface of said envelope; said flashproducing means principally comprising a mixture of a predetermined amount of selected, solid, oxygen-liberating substance and a predetermined amount of selected, metallic substance which when ignited react with one another at a predetermined rate under high-pressure conditions to produce a flash of light; and said flash-producing means and said igniter means being so arranged with respect to one another that firing said igniter means ignites said flash-producing means.

References Cited by the Examiner UNITED STATES PATENTS 613,021 10/1898 Schwartz 6731 2,205,081 6/1940 Burrows et al. 67-31 2,263,179 11/ 1941 Lockwood 67-31 2,285,125 6/ 1942 Pipkin 6731 2,291,983 8/ 1942 Pipkin 67--31 2,325,667 8/1943 DeBoer 67-31 2,333,725 ll/ 1943 Kreidler 6731 2,334,155 11/1943 Oram 67-31 2,361,495 10/ 1944 Pipkin 673l 2,375,742 5/ 1945 Kalil et al. 6731 2,798,368 7/ 1957 Anderson 67-31 2,955,447 10/ 1960 Fink et al 6731 FOREIGN PATENTS 120,915 2/ 1946 Australia.

551,670 6/1932 Germany.

737,594 9/ 1955 Great Britain.

OTHER REFERENCES Zirconium Article: The Metallurgy of Zirconium, by Lustman and Kerze, Jr. 1955 Pub. date, page 46.

FREDERICK L. MATTESON, JR., Primary Examiner.

ALDEN D. STEWART, EDWARD J. MICHAEL,

Examiners. 

1. THE PHOTOFLASH LAMP COMBINATION WHICH COMPRISES: AN ENVELOPE FORMED OF HIGH-STRENGTH, LIGHT-TRANSMITTING ORGANIC PLASTIC OF PREDETERMINED THICKNESS ENCLOSING A PREDETERMINED VOLUME OF AIR AT ATMOSPHERIC PRESSURE AND SEALED AGAINST RUPTURE UNDER CONDITIONS OF HEAT AND PRESSURE; METALLIC SUPPORT MEANS EXTENDING INTO SAID ENVELOPE; IGNITER MEANS SUPPORTED WITHIN SAID ENVELOPE BY SAID METALLIC SUPPORT MEANS AND ADAPTED TO BE FIRED TO PRODUCE A LIM TED COMBUSTION REACTION; FLASH-PRODUCING MEANS ENCLOSED BY SAID ENVELOPE AND SUBSTANTIALLY PHYSICALLY SEPARATED FROM SAID IGNITER MEANS AND ANY METALLIC SUPPORT MEANS; SAID FLASH-PRODUCING MEANS PRINCIPALLY COMPRISING A MIXTURE OF A PREDETERMINED AMOUNT OF SELECTED, FINELY DIVIDED, SOLID, OXYGEN-LIBERATING SUBSTANCE AND A PREDETERMINED AMOUNT OF SELECCTED, FINELY DIVIDED, METALLIC SUBSTANCE WHICH WHEN IGNITED REACT WITH ONE ANOTHER AT A PREDETERMINED RATE UNDER HIGH-PRESSURE CONDITIONS TO PRODUCE A FLASH OF LIGHT; AND SAID FLASH-PRODUCING MEANS AND SAID IGNITER MEANS BEING SO ARRANGED WITH RESPECCT TO ONE ANOTHER THAT FIRING SAID IGNITER MEANS IGNITES SAID FLASH-PRODUCING MEANS. 